}
// Work out the total number of bits for this many decks
// See http://crypto.stackexchange.com/q/41886
- var gainedBits = Math.log2(factorial(52 * numberOfDecks));
+ var gainedBits = 0;
+ // Equivalent of Math.log2(factorial(52*numberOfDecks))
+ // which becomes infinity for numberOfDecks > 4
+ for (var i=1; i<=52*numberOfDecks; i++) {
+ gainedBits = gainedBits + Math.log2(i);
+ }
var lostBits = 52 * Math.log2(factorial(numberOfDecks));
var maxBits = gainedBits - lostBits;
// Convert the drawn cards to a binary representation.
// Create a normalized string of the selected cards
var normalizedCards = cards.join("").toUpperCase();
// Convert to binary using the SHA256 hash of the normalized cards.
- // If the number of bits is more than 256, multiple rounds of hashing
+ // If the number of bits is more than 256, multiple hashes
// are used until the required number of bits is reached.
var entropyBin = "";
var iterations = 0;
while (entropyBin.length < numberOfBits) {
- var hashedCards = sjcl.hash.sha256.hash(normalizedCards);
- for (var j=0; j<iterations; j++) {
- hashedCards = sjcl.hash.sha256.hash(hashedCards);
- }
+ var hashedCards = sjcl.hash.sha256.hash(normalizedCards + ":" + iterations);
var hashHex = sjcl.codec.hex.fromBits(hashedCards);
for (var i=0; i<hashHex.length; i++) {
var decimal = parseInt(hashHex[i], 16);